Marvel is even offering "Pet Week" through Marvel Digital Comics. They're offering a chance to check out your 'favorite' stories with Marvel's Mightiest animals for free. You can read them here: http://www.marvel.com/news/comicstories.7514
You can read about Lockjaw, Redwing, Hairball, Lockheed and Frog Thor trying to save the planet in Lockjaw And The Pet Avengers #1 on May 13, 2009. It's written by Chris Eliopoulos and drawn by Ig Guara.